The invention relates to a method for sorting items of mail destined for addresses/delivery points within a predefined delivery area into a delivery sequence by means of a sorting arrangement comprising:
an input for the purpose of feeding into the arrangement successive items of mail carrying address information; PA1 a reading device for the purpose of reading the address information on the items of mail fed into the arrangement; PA1 a control device for the purpose of analyzing the address information retrieved from the items of mail and allocating a sequence indication to the item of mail in question; PA1 a number of similar deposit devices, numbered 1, 2, . . . , n in sequence, in which to deposit the items of mail, PA1 (a) a first sorting run in which: PA1 (b) a second sorting run in which: PA1 (c) a bundling stage in which the items of mail from the successive deposit devices are bundled while retaining the order in which they were deposited in each deposit device. PA1 the delivery area comprises a number (.gtoreq.2) of delivery runs; PA1 the indication of sequence allocated by the control device during the first sorting run represents a pair of numbers (j,k), with a first number j=1, 2, . . . , n and a second number k=1, 2, . . . , n, the allocated number pairs forming matrix positions within an (n.times.n) matrix, each matrix position corresponding with a delivery point within a delivery run in the delivery area, and the matrix positions being grouped per delivery run into non-overlapping (p.times.q) submatrices of the (n.times.n) matrix; PA1 during the first and second sorting runs, each item of mail is deposited in a deposit device with a sequence number in accordance with the first number, respectively the second number, of the allocated number pair, and PA1 during the bundling stage, for a certain delivery run, the items of mail from the deposit devices with the sequence numbers in accordance with the numbers k corresponding to that delivery run are bundled in succession, in the order of said numbers,
said method comprising:
items of mail are fed into an input; PA2 the reading device reads the address information on the items of mail; PA2 the control device, on the basis of the retrieved address information, allocates a sequence indication to each item of mail, and PA2 each item of mail is deposited in a deposit device with a first sequence number derived from the sequence indication allocated to the item of mail in question; PA2 the items of mail deposited during the first sorting run are taken from the successive deposit devices with sequence numbers 1 . . . n and again fed into an input of the arrangement, and PA2 each item of mail is again deposited in a deposit device with a second sequence number, derived from the sequence indication allocated to the item of mail in question;
In the description of the method a number of terms will be used, with the following definitions in this context.
Mail processing comprises the collection of items of mail from various senders, sorting according to destination, transport, and distribution by postmen around delivery points of addressees, such as home addresses.
A delivery area is defined as a geographically delineated section of the operating area of a mail-processing organization, said delivery area generally being subdivided into a number of delivery runs. When in a certain delivery area sorting into delivery sequence takes place, this occurs for the items of mail destined for the organization's own delivery area; in the delivery area in question, the items of mail for other delivery areas will be sorted according to different delivery areas only, and they will only be sorted according to delivery sequence once they have reached those other delivery areas.
A delivery run is defined as a predetermined, most suitable, postman's walk along a given number of delivery points, e.g. home addresses, for items of mail in a section of a delivery area. The number of delivery points included in a certain delivery run, and the route followed by the postman in question to deliver the items of mail destined for that run, have been chosen so as to enable delivery along the entire route to take place at least once per day. As a matter of fact, whenever the text refers to walking, any other means of locomotion (e.g. bicycle or motorcar) may apply.
A sorted delivery run is defined as a collection of items of mail, destined for delivery points within the relevant delivery run, sorted according to the sequence of the delivery points along the postman's walk of the delivery run.
A sorted delivery run may have been subdivided during the sorting process into a number of sections with equal numbers of delivery points, in which the sections, placed in consecutive order, result in the sorted delivery run. Each of the sections, hereinafter referred to as delivery segments, may include one or more dummy delivery points at which no item of mail will ever have to be delivered. Said dummy delivery points may for example serve to make up a suitable number of delivery points in a delivery segment.
A method for sorting items of mail in sequence is disclosed in U.S. Pat. No. 5,009,321.
In the method according to said prior-art technique, the number of items of mail to be sorted is first sorted according to delivery run; U.S. Pat. No. 5,009,321 describes how this is followed by a sorting process for each delivery run, with the result that the delivery run is broken up into as many sections, delivery segments, as there are stackers in the sorting arrangement used. Upon completion of the sorting process, in which the items of mail for a certain delivery run are processed into a number of successive sorting runs, the items of the first delivery segment are in the first stacker, in the order in which they were deposited, the items of the second delivery segment are in the second stacker, and so forth. Said method uses a relatively small number of sorting arrangements, with a limited number of stackers; a number of 20 is mentioned. It is assumed that the items of mail will have been presorted according to delivery run, so each time, the items for a single delivery run can be fed into such a relatively small sorting arrangement. If larger numbers of items of mail need to be processed in a certain location, this requires, if the sorting process described is to be adhered to, a (large) number of such small arrangements, and the transport to, from, and between the arrangements will become a bottleneck preventing an efficient process. If larger sorting arrangements are used, which in this context means with a larger number of stackers or other deposit devices, the sorting process according to the prior-art technique cannot be used as it is. This is because the prior-art method does not provide the means of efficient use of such larger sorting arrangements, as too much time would be involved with collecting the items of mail for a delivery run from the larger number of deposit devices, and the risk of errors made by the operators as a result of the complexity of the sorting process would be relatively large. In addition, as a result of the fact that sorting into a delivery run must first take place before sorting according to delivery point can take place, the number of sorting runs forms an obstacle. Finally, there is the drawback that the number of delivery points per delivery run is more or less fixed, as smaller numbers render the prior-art method less efficient, whereas the number is limited when using a sorting arrangement with the proposed small number of deposit devices.
Even so, larger sorting arrangements can be provided with deposit devices other than stackers, such as bins that can be placed into the arrangement and subsequently removed, in which the items of mail are posited after sorting.